Why Are Halibut So Big?

& Other Halibut Basics

people holding large halibut

Discover Some Fantastic Facts About the World’s Largest Flatfish

  1. An Alaskan halibut can grow to be 8 feet long and 5 feet wide, and weigh 500 pounds.
  2. Because of their size, adult halibut have few predators—mainly sharks, marine mammals, and humans.
  3. Their large size and delectable white meat make halibut a prized target for both commercial and sport fishermen, as well as an important subsistence resource. Halibut is one of Alaska’s most valuable fisheries.
  4. Huge halibut are called “barn doors”; small halibut are “chickens.”
  5. “Barn door” halibut are typically females. Females grow much larger than males, which rarely reach a length of 3 feet.
  6. Mother halibut get more prolific as they get bigger. A 50-pound female produces about 500,000 eggs. A 250-pound female can produce 4 million eggs!
  7. Halibut have been getting smaller for their age since the 1970s. By the 2000s, an average 12-year-old halibut weighed half as much as one in the 1980s. The reasons for the decrease in size are unknown, but competition for food, climate effects, and fishing effects are possible causes.


Halibut can be found throughout most of the marine waters of Alaska – as far north as Nome, along the Aleutian Chain, and throughout the waters of the southeastern Alaska panhandle. Halibut can also be found along the continental shelf as far south as southern California, as well as along the coasts of Japan and Russia. Halibut are usually on or near the bottom over mud, sand, or gravel banks. Most are caught at depths of 90 to 900 feet, but halibut have been recorded at depths up to 3,600 feet. As halibut mature, they migrate in a clockwise direction in the Gulf of Alaska, countering the drift of eggs and larvae. Halibut tagged in the Bering Sea have been caught as far south as the coast of Oregon, a migration of over 2,000 miles. Halibut also move seasonally between shallow waters and deep waters. Mature fish move to deeper offshore areas in the fall to spawn, and return to nearshore feeding areas in early summer. It’s not yet clear if fish return to the same areas to spawn or feed year after year.


The most popular method uses circle hooks baited with herring, fished on the bottom with cannonball weights up to 36 oz. on a slider. You can also use the head, tail, fins, and/or viscera (but only these parts) of sport-caught salmon as bait. Halibut eat almost anything they can catch, so jigging with J hooks baited with octopus or whole herring, or with lead-head jigs or other artificial lures is also effective.

Halibut that are small enough to be lifted aboard can be gaffed. Avoid using a gaff with a straight hook. Stick the gaff in the fish behind the gills and above the gut cavity and pull the fish into the boat in a continuous motion. Be ready to subdue the fish with several good whacks above the eyes and bleed it by cutting a few gill arches, the caudal peduncle (narrow part in fron of the tail), or both. Never gaff a halibut you intend to release.

Very large halibut can be shot in the brain with a .22 caliber pistol or small shotgun, but make sure you have control of the fish before doing this. The brain is located just behind (toward the tail) the upper eye. Large halibut can also be harpooned or stuck with a shark hook attached to a bullet buoy. The harpoon head must penetrate the fish completely in order to hold reliably. Large halibut can also be subdued without bringing them aboard by tying them to boat cleats with a tail loop and another loop of rope through the mouth and gills. The fish can then be bled outside the boat.


Success rates vary widely from vessel to vessel and from day to day, but good catches are made from mid-May through mid-September throughout Alaska. Many believe the best fishing is just before, during, and after high slack tide. This is the easiest time to keep your tackle on or near the bottom. Use modern, small diameter lines to minimize stretch and drag when fishing deep or in heavy currents.

Link to Original Articles: https://www.fisheries.noaa.gov/feature-story/7-reasons-why-size-matters-halibut  & https://bighalibut.com/services/alaskan-halibut-facts/

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